Vibration when running, rough idle
 

My 2008 Mazda 3 2.0L has a few problems which seem related. I'll get right to the point! Here are its current problems:

*The engine is naturally loud and particularly vibrating at all times, enough to be mildly annoying and enough so that I know something is off.

*It idles loudly and a little rough.

*Whenever I am accelerating, no matter how lightly I push the pedal, the whole car vibrates/shakes. It's not horrible, but it is annoying. It is also getting worse. If I accelerate very quickly, I can feel the pedal shuddering.

*When maintaining speed, especially highway speeds, the vibration is enough to cause annoying rattles in the cabin.

*After driving for a few minutes, when I come to stop the engine pulses rhythmically, shuttering for a couple seconds at a time, before eventually idling "normally" after a minute or two.

In short... the engine is loud and vibrates a lot.

The check engine light is not on.

At first, I thought it was a bad engine mount, which I've heard is a common problem, but would that really cause the engine to run poorly?

Any help would be very much appreciated!

Hey, I know this post was from a couple of months ago but did you ever find out what the issue was? I'm experiencing similar issues with my 2010 Mazda 3. I recently had my breaks and spark plugs done and noticed vibration/shuttering sounds coming from the cabin. I had my neighbor run a diagnostic test today and nothing came up, no check engine light is on either. When he looked at my new plugs, he discovered that they are not the recommended plugs for the vehicle by looking at my owners manuel. We are going to order the right plugs and change them out to see if that resolves the issue. Also, I would try to change the cabin filter as well if you haven't already. It could be one of those two things, if you haven't already fixed the issue!

I brought it to my mechanic, who pointed out that the engine was not original in my car, but it had been replaced with a used one. Without an engine light on, he didn't want to tear the engine apart looking for the issue. He suspected it is something inside the engine, perhaps the camshaft.

So, essentially I just have to deal with it until something more happens. I have gotten used to it.